Operating procedures for public carrier networks are governed by a set of network engineering and operation policies. Some policies apply to a whole network; while others are defined for parts of the network which include regions, areas, platform domains, and sections. Network operation policies are regularly reviewed by operators, and changes are made to accommodate emerging traffic patterns, new technologies, or customer demands. The scope of a policy may vary for each application. The same policy can be applied to different sections of a global transport network either simultaneously or in different time-frames. In general, network operation policies are established to serve many purposes. Some examples are traffic management, maintenance, security, circuit quality-of-service (QoS), etc.